/* Filename: rcver.c
 * Description: 报式socket
 * Last modified: humble 2020-06-14 12:33
 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include "proto.h"

#define IPSTRSIZE (40)

static void usage(void);

int main(int argc, char **argv)
{
    int sd;
    struct sockaddr_in laddr,raddr;
    struct msg_st rbuf;
    socklen_t raddr_len;
    char ipstr[IPSTRSIZE];

    if(argc != 1){
        fprintf(stderr, "argc !=1");
        usage();
        exit(1);
    }

    sd = socket(AF_INET, SOCK_DGRAM, 0/*IPPROTO_UDP*/);
    if(sd < 0){
        perror("socket()");
        exit(1);
    }

    laddr.sin_family = AF_INET;
    laddr.sin_port = htons(atoi(RCVPORT));
    inet_pton(AF_INET, "0.0.0.0", &laddr.sin_addr);

    if(bind(sd, (void *)&laddr, sizeof(laddr)) < 0){
        perror("bind()");
        exit(1);
    }

    /* 重要：若没初始化该值，则会导致第一次收到数据出错 */
    raddr_len = sizeof(raddr);

    while(1){
        recvfrom(sd, &rbuf, sizeof(rbuf), 0, (void *)&raddr, &raddr_len);
        inet_ntop(AF_INET, &raddr.sin_addr, ipstr, IPSTRSIZE);
        printf("---MESSAGE FROM:%s:%d---\n", ipstr, ntohs(raddr.sin_port));
        printf("name:%s\n", rbuf.name);
        printf("math:%d\n", ntohl(rbuf.math));
        printf("chinese:%d\n", ntohl(rbuf.chinese));
    }

    close(sd);
    return 0;
}

static void usage(void)
{
#define USAGE "Usage:\n\
  Helloworld\n"
    printf(USAGE);
}
